This invention relates generally to sanitizing swimming pools and, more specifically, is directed to a dispenser for dispensing swimming pool chemical into the surrounding water while the dispenser is immersed in the water.
Sanitizing agents and bacteria-killing agents that are water soluble must be added regularly to swimming pool water to kill bacteria and inhibit growth of organic matter so that a safe and comfortable swimming environment can be maintained. Chlorine, or compounds of chlorine, typically are used for this purpose.
Pool chemicals can be added to swimming pools either through in-line flow circuits, through broadcast distribution of granular product or concentrated dosages of liquid product. Whatever the form of administering the pool chemical, pool water should be maintained at a desired chlorine concentration ranging anywhere from about 0.1 to about 25.0 parts per million by weight residual chlorine. A preferable range is from about 0.3 to about 5.0 parts per million by weight. Maintaining this desired range, however, is difficult because the chlorine concentration in the water is affected by a multitude of factors, such as pool water temperature, the amount of sunlight, rain, the number of bathers, the size of the pool and other factors.
Calcium hypochlorite compositions are a well-known source of available chlorine for disinfecting and sanitizing water supplies, especially swimming pool water. Calcium hypochlorite is a highly soluble basic material that dissolves rapidly in water in comparison to the other compounds which are sources of available chlorine, such as trichloroisocyanurates that dissolve much more slowly without leaving insoluble residues.
Trichloroisocyanurates are normally utilized in tablet form and are typically added to a pool in a skimmer, which is in the in-line flow circuit of water from the pool, or by using a floating feeder device. These tablets normally dissolve slowly over a 1 or 2 week period, giving continuous protection to the pool with minimal effort by the pool owner.
In contrast, however, calcium hypochlorite dissolves very quickly and leaves a small amount of insoluble residue. The residue will remain in the bottom of pool chemical feeders that are employed in skimmer or which will precipitate to the bottom of the pool if the chemical is delivered by broadcast spreading. However, because of the quick dissolution rate calcium hypochlorite application requires daily attention by the maintainer of the pool if even chlorination levels are to be maintained.
Alternately, periodic treatments with large doses of calcium hypochlorite are employed. This is less desirable since it results temporarily in a higher than normal chlorine concentration in the pool water which is a shock treatment, spiking the chlorine concentration in the swimming pool water. Periodic treatments can also be administered through a skimmer.
Even where containers for calcium hypochlorite have been used to dispense the chemical into pool water, adjustability of the container or dispenser to selectively control the feed rate of the chemical in response to changing demand has been a limiting feature. There also has been no true or simple indicator of when the pool chemical container or feeder is empty.
Additionally, the broadcast method of treating pools with granular calcium hypochlorite and the placing of calcium hypochlorite briquettes in a skimmer require the maintainer of the pool to handle the chemical.
Thus, the use of calcium hypochlorite as a pool sanitizer can potentially be inconvenient because of the fast dissolution rate and the frequent attention required on the part of the owner.
These problems are solved in the design of the present invention wherein a pool chemical dispensing capsule is formed of a material which holds the pool chemical and signals when the chemical is fully dispensed, requiring the replacement with a new chemical dispensing unit.